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Biology > SB4 - Natural selection and Genetic modification > Flashcards

SB4 - Natural selection and Genetic modification Flashcards

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1
Q

Who developed the theory of specification?

A

Alfred Russel Wallace

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2
Q

Who is Charles Darwin?

A
  • Scientist and naturalist
  • Put forward the theory of evolution
    –> Supported by experimentation + his knowledge of
    geology and fossils that he discovered on a round the world expedition
  • Published ‘On the Origin of Species’
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3
Q

When did Charles Darwin publish ‘On the Origin of Species’?

A

1859

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4
Q

Why does variation exist within species?

A

As a result of mutations in DNA

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5
Q

What is survival of the fittest?

A

Organisms with characteristics most suited to the environment are more likely to survive to reproductive age and breed successfully

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6
Q

What is the process of speciation?

A
  • Alleles which provide a survival advantage are selected for through natural selection.
  • Populations of a species can become isolated
  • Different alleles may be advantageous in the new environment, leading to them being selected for
  • Over time the selection of different alleles will increase the genetic variation between the two populations
  • When they are no longer able to breed together to produce fertile offspring, a new species has formed
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7
Q

Why was there a lot of controversy surrounding the theory of evolution?

A
  • It contradicted the idea that God was the creator of all species on Earth
  • There was not enough evidence at the time as few studies had been done on how organisms change over time
  • The mechanism of inheritance and variation were not known at the time
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8
Q

When are bacteria labelled as resistant?

A

When they are not killed by antibiotics which previously were used as cures against them

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9
Q

How are new strains of a bacteria created?

A

Mutations during reproduction can result in new genes, such as the gene for antibiotic resistance

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10
Q

How does the presence of new, resistant bacteria supportive of Darwin’s theory of evolution?

A

Those with antibiotic resistance can reproduce and pass on the
advantageous gene to their offspring

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11
Q

Give an example of a bacteria which is resistant to antibiotics

A

MRSA

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12
Q

What is MRSA also known as?

A

Superbug

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13
Q

Where is MRSA common?

A

Common in hospitals: spreads when doctors and nurses move to different patients

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14
Q

What does fossil evidence show?

A

How developments in organisms arose slowly

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15
Q

What techniques can we use to date fossils?

A

Carbon dating

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16
Q

Name some human ancestors

A
  • Ardi
  • Lucy
  • Homo Habilis
  • Homo Erectus
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17
Q

Name the human ancestors in the order of the oldest to the youngest

A
  • Ardi
  • Lucy
  • Homo habilis
  • Homo Erectus
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18
Q

How long ago has Ardi lived?

A

4.4 million years ago

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19
Q

Describe Ardi’s structure

A

Contains many ‘humanoid’ features but also resembles an ape:
* May have been able to walk upright
* Very long arms
* Very long toes that stuck out on the side

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20
Q

How long ago has Lucy lived?

A

3.2 million years ago

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21
Q

Describe Lucy’s structure

A
  • Could walk upright
  • Small, chimp like skull and brain
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22
Q

How long ago has Homo Habilis lived?

A

2.4 - 1.4 million years ago

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23
Q

Describe Homo Habilis’ structure

A
  • Short
  • Long arms
  • Walked upright
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24
Q

How long ago has Homo Erectus lived?

A

1.8 - 0.5 million years ago

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25
Q

Describe Homo Erectus’ structure

A
  • Tall
  • Strongly built
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26
Q

What does the discovery of Homo Erectus prove?

A

That humans originated from Africa

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27
Q

What are the names of the scientists that discovered homo erectus / habilis?

A

Louis and Mary Leakey

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28
Q

What can we use as part of evidence for human evolution?

A

Stone tools

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29
Q

What do stone tools show about us?

A

Stone tools have become more complex as our brains evolved in complexity

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30
Q

Describe the types of stone tools that Homo Habilis used

A

Used basic pebble tools created by smashing rocks together
—> Tools had simple uses

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31
Q

Describe the types of stone tools that Homo neanderthalensis & Sapiens used

A

Used pointed arrowheads, spears and hooks
—> Enabled more advanced tasks to be carried out, such as catching fish

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32
Q

What methods do we use to date stone tools?

A
  • Radiometric carbon dating
  • Stratifying rock layers
33
Q

Explain what Radiometric carbon dating is

A

We do this by looking at the natural radioactive decay of an isotope of Carbon (Carbon-14) we can estimate how long ago an organism lived

34
Q

Explain what Stratifying rock layers is

A

We do this by looking at the layer of sediment in which a rock. Each layer of sediment, and everything within it, must have been formed at the same time
—> Therefore, we can date once-living fossils in this layer

35
Q

What is a pentadactyl limb?

A

A limb with five digits

36
Q

What is genetic variation?

A

The characteristics of individuals vary due to differences in genes

37
Q

Name the ways we can classify organisms

A
  • Three Domains system
  • 5 Kingdoms system
38
Q

What are the groups in the 5 Kingdoms system?

A
  • Animals
  • Plants
  • Fungi
  • Prokaryotes
  • Protists
39
Q

What is each kingdom then subdivided into?

A

A phylum, class, genus, order and species

40
Q

What is the binomial naming system based on?

A

Genus and species

41
Q

What are the groups in the three domain system?

A
  • Archaea
  • Bacteria
  • Eukaryota
42
Q

What is Archaea?

A

Primitive bacteria which live in extreme environments such as hot springs

43
Q

What is Bacteria?

A

True bacteria (despite having similar features to archaea)

44
Q

What is Eukaryota?

A

Organisms who have a nucleus enclosed in membranes, includes the kingdoms protists, fungi, plants and animals

45
Q

Explain how genetic analysis has led to the suggestion of the three domains system rather than the five kingdoms classification method

A

Developments in science such as the improvement of the microscope and increased knowledge of biochemistry found that some species were more distantly related than first thought

46
Q

What is selective breeding?

A

When humans choose which organisms to breed in order to produce offspring with a certain desirable characteristic

47
Q

Describe the process of selective breeding

A

1) Parents with desired characteristics are chosen

2) They are bred together

3) From the offspring those with desired characteristics are bred together

4) The process is repeated many times until all the offspring have the desired characteristic

48
Q

What are the problems with selective breeding?

A
  • Can lead to inbreeding
  • Offspring can have a greater chance of genetic defects being present
  • Lack of genetic variation
  • Ethical issues associated with selective breeding
49
Q

What are the issues with inbreeding in selective breeding?

A

If the environment changes or there is a new disease , the species could become extinct as they all have the same genetic make-up

50
Q

How does selective breeding cause ethical concerns?

A

Many people consider it unethical to selectively breed for characteristics wanted by humans if it means that the offspring will suffer, or have a reduced quality of life as a result

51
Q

How does selective breeding lead to inbred species?

A

Breeding those with similar desirable characteristics means it is likely you are breeding closely related individuals

—> Results in the reduction of the gene pool , as the number of different alleles reduce (as they mostly have the same alleles)

52
Q

What are the benefits of selective breeding?

A
  • Greatly increase the yield of a particular crop by selectively breeding only individuals that produce higher quality or a larger mass of food
  • Individual plants or animals can be bred to be resistant to a particular disease
53
Q

What is tissue culture?

A

A method of culturing living tissue

54
Q

What are some uses of tissue culture?

A
  • Can culture animal and human tissues outside of the body
  • Can produce an entire field of identical cloned crops using just a small cutting
55
Q

How would you preform a tissue culture on plants?

A
  1. Take the plant that you would like to clone
  2. Using tweezers, remove a piece of tissue from a fast-growing region of the plant, e.g the root or shoot tip .
  3. Using aseptic technique, place the tissue on a special growth medium (containing hormones and nutrients).
  4. Once the tissue has developed enough (e.g produced shoots and roots), it can be transferred to compost for further growth .
56
Q

What are the benefits of tissue culture?

A
  • Produces lots of offspring w/ desirable features
  • Increasing the number of crops resistant to bad weather
  • Can help extremely endangered species, or even bring back species that have become extinct
57
Q

What are the risks of tissue culture?

A
  • It may lead to human cloning
  • Clones have a low survival rate, and tend to have some genetic problems
  • Gene pool is reduced through producing clones - low diversity of population
58
Q

What is genetic engineering?

A

Modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic

59
Q

What are the stages of genetic engineering?

A

1) Genes from chromosomes are ‘cut out’ using restriction enzymes

2) The same restriction enzymes are used to cut the vector (such as a virus or bacterial plasmid) into which the genes will be placed

3) Ligase enzyme is used to attach the sticky ends of the gene and the vector together, to produce a recombinant gene product.

4) The vector is placed in another organism at an early stage in development so the desired gene moves into its cells and cause the organism to grow with the desired characteristics.

60
Q

Where is the vector placed in plants during genetic engineering?

A

Into meristematic cells which can then produce identical copies of the modified plant

61
Q

What are genetically modified crops engineered to do?

A

To be resistant to insects and to herbicides
—> Results in increased yields as less crops will die

62
Q

What is genetic modification in medicine used for?

A

Gene therapy

63
Q

What is gene therapy?

A

Involves transferring normal genes (not faulty) into patients so the correct proteins are produced

64
Q

What are the benefits of genetic engineering?

A
  • Can mass produce certain hormones in microorganisms
  • Can improve yields in agriculture
  • Crops w/ extra vitamins can be produced in areas where they are difficult to obtain
65
Q

How does genetic engineering improve yields?

A
  • Improving growth rates
  • Introducing modifications that allow the crops to grow in different conditions
  • Introducing modifications that allow plants to make their own pesticide or herbicide
66
Q

What are the risks of genetic engineering?

A
  • Might have an effect on wild flowers & therefore insects
  • People are worried that we do not completely understand the effects of GM crops on human health
  • Pose a selection pressure
67
Q

How does genetic engineering posing a selection pressure a risk?

A

Could lead to increased resistance in other species, creating super weeds and pests

68
Q

How might genetic engineering have an effect on wild flowers & insects?

A
  • GM crops are infertile and these genes could spread into wild plants, leading to infertility in other species
    —> This affects the entire environment
  • Growing with herbicides and pesticides can kill insects and other plants, which would reduce biodiversity.
69
Q

What is Bacillus thuringiensis?

A

The name of a bacteria that produces toxins that kill insect larvae

70
Q

Why does having BT a useful function for crops?

A

Increases their insect resistance

71
Q

How do we create BT crops?

A

Genes are cut out from the bacteria using restriction enzymes , and re-inserted into the crop using ligase

72
Q

What are some benefits of BT crops?

A

Less of the crop gets eaten by insects, increasing the crop yield and profits

73
Q

What are some risks of BT crops?

A

We don’t know if the toxin has any effect on human health

74
Q

What methods can we use to cope with the demands of a growing human population?

A
  • Fertilisers
  • Biological control
75
Q

How do fertilisers help to cope with the demands of a growing human population?

A

Fertilisers provide useful nutrients to plants, making them more resistant to environmental conditions and able to grow faster and larger —> Resulting in increased crop yields

76
Q

How do Biological control help to cope with the demands of a growing human population?

A

Another species can be used to maintain / control another species but it does reduce biodiversity and has a knock-on effect across the whole ecosystem

77
Q

What is Biological control?

A

The use of certain species to control population of other species

78
Q
A

Biology (11 decks)

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